Photon tunneling time: Superluminal velocity for 1-D tunneling through a metallic barrier

In this paper, we study the transmission of an optical wave packet through a metallic slab. We show that this problem is a true 1-D optical tunneling. For normal incidence and for incident frequency lower than the plasmon frequency, evanescent waves are created in the metal. In the case of a Drude model without loss, equations are formally equivalent to quantum mechanics ones. We also calculate the tunneling time and show that for a “thick” barrier the time delay is negative and leads to superluminal tunneling velocity. These results remain valid in the case of a real metal with energy loss. We briefly discuss the possibility of an experiment.